The albedo of the subsurface scattering in the Principled BSDF was just a blend between the base and subsurface color. The albedo was also used for weighting the BSSRDF closures. This caused a constant backscatter color.
With this patch, the subsurface color is applied as the albedo and the blended color is only used for weighting the closures, which results in physically plausible backscatter colors, depending on the depth of the subsurface scattering rays.
Here is a comparison with base color = (0.0, 1.0, 1.0) and subsurface color = (1.0, 0.0, 0.0):